US20150116706A1 - Apparatus for performing a sensing application - Google Patents

Abstract

An apparatus for performing a sensing application includes a reservoir to contain a solution, a dispenser to dispense the solution from the reservoir, and a substrate having a plurality of nano-fingers positioned to receive the dispensed solution, in which the plurality of nano-fingers are flexible, such that the plurality of nano-fingers are configurable with respect to each other. The apparatus also includes an illumination source to illuminate the received solution, an analyte introduced around the plurality of nano-fingers, and the plurality of nano-fingers, in which light is to be emitted from the analyte in response to being illuminated. The apparatus further includes a detector to detect the light emitted from the analyte.

Description

BACKGROUND
• Raman scattering optical spectroscopy employs an emission spectrum or spectral components thereof produced by inelastic scattering of photons by an internal structure of the material being illuminated. These spectral components contained in a response signal (for instance, a Raman signal) are to facilitate determination of the material characteristics of an analyte species including identification of the analyte.
• The Raman signal level or strength is often significantly enhanced by using a Raman-active material (for instance, Raman-active surface), however. For instance, the Raman scattered light generated by a compound (or ion) adsorbed on or within a few nanometers of a structured metal surface can be 10³-10¹²times greater than the Raman scattered light generated by the same compound in solution or in the gas phase. This process of analyzing a compound is called surface-enhanced Raman spectroscopy (“SERS”). In recent years, SERS has emerged as a routine and powerful tool for investigating molecular structures and characterizing interfacial and thin-film systems, and even enables single-molecule detection.
BRIEF DESCRIPTION OF THE DRAWINGS
• Features of the present disclosure are illustrated by way of example and not limited in the following figure(s), in which like numerals indicate like elements, in which:
• FIGS. 1A-1C, respectively, show simplified cross-sectional side views of apparatuses for performing a sensing application, according to examples of the present disclosure;
• FIG. 2A shows an isometric view of an array of nano-fingers for use in a sensing application, according to an example of the present disclosure; and
• FIGS. 2B and 2C show cross-sectional views along a line A-A, of the array shown inFIG. 2A, according to examples of the present disclosure;
• FIG. 3 shows a simplified block diagram of a sensing apparatus for use in a sensing application, according to an example of the present disclosure;
• FIG. 4 shows a flow diagram of a method for performing a sensing application on an analyte introduced onto a plurality of nano-fingers, according to an example of the present disclosure;
• FIG. 5 shows a flow diagram of a method for communicating electrical signals representative of the detected Raman scattered light to a destination receiver, according to an example of the present disclosure and
• FIG. 6 illustrates a schematic representation of a sensing application apparatus, such as any of the sensing application apparatuses depicted inFIGS. 1A-1C, according to an example of the present disclosure.
DETAILED DESCRIPTION
• For simplicity and illustrative purposes, the present disclosure is described by referring mainly to an example thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures have not been described in detail so as not to unnecessarily obscure the present disclosure.
• Throughout the present disclosure, the terms “a” and “an” are intended to denote at least one of a particular element. As used herein, the term “includes” means includes but not limited to, the term “including” means including but not limited to. The term “based on” means based at least in part on. In addition, the term “light” refers to electromagnetic radiation with wavelengths in the visible and non-visible portions of the electromagnetic spectrum, including infrared and ultra-violet portions of the electromagnetic spectrum.
• Disclosed herein are an apparatus and a method for performing a sensing application, such as, SERS, enhanced luminescence, enhanced fluorescence, etc. The apparatus includes a reservoir, a dispenser to dispense a solution contained in the reservoir, a substrate having a plurality of nano-fingers positioned to receive the dispensed solution, an illumination source, and a detector. The nano-fingers are flexible, such that, the nano-fingers are configurable with respect to each other. In one regard, the nano-fingers may have a first configuration prior to a measurement being made and a second, different configuration during performance of the measurement. The illumination source is to illuminate the received solution, an analyte introduced around the plurality of nano-fingers, and the plurality of nano-fingers. In addition, the detector, which may comprise a spectrometer, is to detect light, such as, Raman scattered light, emitted from the analyte in response to being illuminated by light from the illumination source. The detector is also to convert the detected light into electrical signals representative of the detected light. The apparatus may also include an interface through which the electrical signals are communicated. The interface comprises a wireless and/or wired interface.
• Generally speaking, the apparatus disclosed herein performs both the collection and measurement of an analyte and thus, the apparatus may be used outside of a laboratory environment. In addition, because the electrical signals representative of the detected Raman scattered light are communicated externally to the apparatus, a device external to the apparatus may perform relatively complicated operations, such as, processing of the detected Raman scattered light. As such, the apparatus disclosed herein may have a relatively small and compact form factor and may thus suitable for hand-held use as well as for deployment in the field. In addition, the sensing application apparatus disclosed herein may be fabricated at a relatively lower cost as compared with sensing equipment that also perform processing of detected Raman scattered light.
• With reference first toFIG. 1A, there is shown a simplified cross-sectional side view of anapparatus100 for performing a sensing application, according to an example. It should be understood that theapparatus100 depicted inFIG. 1A may include additional elements and that some of the elements described herein may be removed and/or modified without departing a scope of theapparatus100. It should also be understood that the elements depicted inFIG. 1A are not drawn to scale and thus, the elements may have different relative sizes with respect to each other than as shown therein.
• Theapparatus100 is depicted as including areservoir102, adispenser104, anillumination source106, adetector108, aninterface110, astage112, asubstrate114, and a plurality of nano-fingers116. The components of thesensing application apparatus100 are further depicted as being integrated into a single housing140. In this regard, thesensing application apparatus100 may be fabricated as a portable, hand-held device. That is, the housing140 may be sized such that a user may carry theapparatus100 in one or both hands. By way of particular example, the housing140 may be less than about 12 inches wide by about 12 inches long by about 4 inches high. In addition, although not shown, the housing140 may comprise an opening through which samples containing analytes, such as, air, water, etc., from a surrounding environment, may be introduced into the housing140 for testing.
• As discussed in greater detail herein below, the plurality of nano-fingers116 are flexible to cause tips of adjacent ones of some of the plurality of nano-fingers116 to be drawn toward each other. In addition, and according to an example, Raman-active material nano-particles (not labeled inFIG. 1A) are provided at least on the tips of the plurality of nano-fingers116 to substantially enhance the emission of Raman scattered light from the analyte. In this regard, as the tips of the nano-fingers116 are drawn together, the Raman-active material nano-particles provided on the tips of some of the adjacent nano-fingers116 may be drawn toward each other such that a relatively small or no gap exists between the Raman-active material nano-particles.
• A nano-finger116 is defined, for instance, as an elongated, nanoscale structure having a length (or height) that exceeds by more than several times a nanoscale cross sectional dimension (for instance, width) taken in a plane perpendicular to the length (for instance, length>3×width). In general, the length is much greater than the width or cross sectional dimension to facilitate bending of the nano-finger116 laterally toward one or more neighboring nano-fingers116. In some examples, the length exceeds the cross sectional dimension (or width) by more than a factor of about 5 or 10. For example, the width may be about 100 nanometers (nm) and the height may be about 500 nm. In another example, the width at the bases of the nano-fingers116 may range between about 10 nm and about 1 micrometer (μm) and the length may range between about 50 nm and 2 μm. In other examples, the nano-fingers116 are sized based upon the types of materials used to form the nano-fingers116. Thus, for instance, the more rigid the material(s) used to form the nano-fingers116, the less the width of the nano-fingers116 may be to enable the nano-fingers116 to be laterally collapsible. In further examples, the nano-fingers116 may form ridges in which two of three dimensions (for instance, length and height) exceed by more than several times a nanoscale cross sectional dimension (for instance, width). The nano-fingers116 may equivalently be referenced as nano-poles or nano-pillars without departing from a scope of theapparatus100.
• InFIG. 1A, thereservoir102 is also depicted as containing asolution120 that is delivered to thedispenser104,droplets122 of which thedispenser104 dispenses onto the nano-fingers116. Thedispenser104 comprises any reasonably suitable type of dispenser that is to controllably dispensesolution120 from thereservoir102 onto the nano-fingers116. Thus, for instance, thedispenser104 is to deliver a fixed volume of thesolution120 onto the nano-fingers116 for quantitative analysis. Examples of suitable types of dispensers comprise autopippetting, thermal actuating, piezoelectric actuating, etc., types of dispensers. By way of particular example, thedispenser104 comprises a type of dispenser that is similar to those used in inkjet printing technology. In addition, a controller (not shown) may operate thedispenser104 to control the delivery of thedroplet122. By way of particular example, thedispenser104 has a resolution of less than about 10 μm, but may be designed to dispensedroplets122 at various other sizes.
• Thesolution120 comprises any reasonably suitable type of fluid that is to be deposited onto the nano-fingers116 and at least partially evaporated. By way of example, thesolution120 comprises a functionalized fluid that is to interact, for instance, bond with, dissolve, or have some other type of reaction with, a particular type or types of analyte molecule. As another example, thesolution120 comprises a fluid that is to be introduced into an environment containing the analyte to be tested, for instance, through intermixing of the analyte into thesolution120. As a further example, thesolution120 comprises a standard fluid of known concentration to be used in recalibrating theapparatus100. In this regard, thereservoir102 and in some examples, thesolution120, generally operates to collect liquid or gas samples and to store the samples prior to being deposited onto the nano-fingers116. In addition, the reservoir102 (and/or the solution120) may operate to filter the samples prior to being dispensed onto the nano-fingers116.
• As also shown inFIG. 1A, thesubstrate114 on which the nano-fingers116 are provided is supported on thestage112. According to an example, either or both of thedispenser104 and thestage112 is movable with respect to each other. Thus, for instance, thedroplet122 may be dispensed onto variously located nano-fingers116 by moving thedispenser104 and/or thestage112 with respect to each other. In addition, thestage112 may be moved as indicated byarrow118 to another location within thesystem100 as shown inFIG. 1A. According to an example, the nano-fingers116 are fabricated to either be hydrophobic or hydrophilic. In this example, subsets of hydrophilic nano-fingers116 may be separated by subsets of hydrophobic nano-fingers116 to substantially maintain separation of thedroplets122 on the nano-fingers116. In addition or alternatively, thesubstrate114 may include alignment markers that theapparatus100 uses to align theillumination source106 and thedetector108 correctly such that the desired area of thesubstrate114 is tested at a given time.
• Theillumination source106 is further depicted as emitting electromagnetic radiation, as represented by thearrow130, which comprises, for instance, an illumination, laser light, etc. By way of example, theillumination source106 comprises a laser that illuminates the tips of the nano-fingers116 as discussed in greater detail herein below. As also shown, thedetector108, which may comprise a spectrometer, captures the Raman scattered light132. In addition, thedetector108 converts the Raman scattered light132 into electrical signals.
• Although asingle illumination source106 has been depicted inFIG. 1A, according to another example, theapparatus100 includes an array ofillumination sources106. In this example, each of theillumination sources106 may emit light at different wavelengths with respect to each other and a shutter system (not shown) may be incorporated into the path(s) of theillumination130 and the Raman scattered light132 to substantially ensure that thedetector108 is able to detect Raman scattered light132 emitted as a result of light respectively received from the array ofillumination sources106.
• According to an example, thedetector108 communicates the electrical signals to theinterface110 through which the electrical signals are to be communicated to a destination receiver (not shown). In this example, the destination receiver may store the electrical signals and/or process the electrical signals to determine, for instance, an identification of the analyte from which the Raman scattered light132 was captured. In any regard, theinterface110 comprises hardware and/or software components that enable the electrical signals to be communicated at least one of wirelessly or through a wired connection. As such, theinterface110 may include a physical interface, such as, an Ethernet or other type of port into which a cable connector may be inserted. In addition or alternatively, theinterface110 includes a wireless interface, including an antenna, that is to communicate the electrical signals as a wireless signal, such as, as an RF signal, a Bluetooth™ signal, a WiFi™ signal, a cellular signal, etc.
• According to another example, thesensing application system100 includes components (not shown) to at least partially process the electrical signals to determine, for instance, an identification of the analyte from which the Raman scattered light132 was captured.
• Thesensing application apparatus100 is further depicted as including anoptional power supply150. Thepower supply150 is considered to be optional because thesensing application apparatus100 may be powered from electricity received through an alternating current power source. In any regard, thepower supply150 may comprise, for instance, a direct current battery or other suitable power supply. An example of a suitable power supply is a radio frequency identification (RFID) powered device. In this example, thesensing application apparatus100 may be powered through electromagnetic radiation received, for instance, from an electromagnetic radiation source (not shown).
• Turning now toFIG. 1B, there is shown a simplified cross-sectional side view of anapparatus100′ for performing a sensing application, according to another example. Theapparatus100′ depicted inFIG. 1B includes many of the same components as those contained in theapparatus100 depicted inFIG. 1A. As such, only those features inFIG. 1B that differ from those ofFIG. 1A are described with respect to theapparatus100′.
• As shown inFIG. 1B, theillumination source106 and thedetector108 are positioned to illuminate the nano-fingers116 and to collect the Raman scattered light132 without requiring that thestage112 substantially move from a position beneath thedispenser104. Theapparatus100′ may thus have a relatively smaller size as compared with theapparatus100 depicted inFIG. 1A. In addition, theapparatus100′ requires less moving elements as compared with theapparatus100 depicted inFIG. 1A.
• As discussed above with respect toFIG. 1A, thestage112 may however be movable with respect to thedispenser104 or vice versa to enabledroplets122 of thesolution120 to be deposited on variously located subsets of nano-fingers116.
• Turning now toFIG. 1C, there is shown a simplified cross-sectional side view of anapparatus100″ for performing a sensing application, according to a further example. Theapparatus100″ depicted inFIG. 1C includes many of the same components as those contained in theapparatus100 depicted inFIG. 1A. As such, only those features inFIG. 1C that differ from those ofFIG. 1A are described with respect to theapparatus100″.
• As shown inFIG. 1C, thesensing application apparatus100″ includes asecond reservoir160 and asecond dispenser162. Thesecond reservoir160 is depicted as containing asecond solution164 that is dispensed onto thesubstrate114 through thesecond dispenser162. Thesecond dispenser162 comprises any reasonably suitable type of dispenser that is to controllably dispense thesecond solution162 from thesecond reservoir160 onto the nano-fingers116. Thesecond dispenser162 may comprise any of the types of dispensers and may be operated in any of the manners discussed above with respect to thedispenser104, for instance, to controllably deliver a fixed volume of thesecond solution164 onto the nano-fingers116.
• According to an example, thesecond solution164 comprises a different composition than thesolution120 contained in thereservoir102. In this regard, thesolutions120 and164 may be deposited onto differently located sets of the nano-fingers116 and testing of an analyte at the differently located sets of nano-fingers116 may be performed. In another example, thesolutions120 and164 may be deposited onto the same set of nano-fingers116 by moving either or both of thestage112 and thedispensers104,162. For instance, thesolutions120 and164 may be mixed as thesolutions120 and164 are deposited onto the nano-fingers116 in instances where a combination of thesolutions120 and162 is not desired or practical until an analyte is to be introduced into theapparatus100″.
• Although thesensing application apparatuses100,100′,100″ inFIGS. 1A-1C have been depicted as including either one or tworeservoirs102,160 and either one or twodispensers104,162, it should be understood that theapparatuses100,100′,100″ may include any reasonable numbers of these elements without departing from the scopes of theapparatuses100,100′,100″. In addition, thesensing application apparatuses100,100′,100″ may includemultiple dispensers104,162 perreservoir102,160.
• Turning now toFIG. 2A, there is shown an isometric view of anarray200 of the nano-fingers116 depicted inFIGS. 1A-1C, according to an example. As shown inFIG. 2A, thearray200 includes thesubstrate114 upon which the nano-fingers116 extend. More particularly, the nano-fingers116 are depicted as being attached to and extending above a surface of thesubstrate114. Thesubstrate114 may be formed of any suitable material, such as, paper, silicon, silicon nitride, glass, plastic, polymer, SiO₂, Al₂O₃, aluminum, etc., or a combination of these materials, etc.
• According to an example, the nano-fingers116 are formed of a relatively flexible material to enable the nano-fingers116 to be laterally bendable or collapsible, for instance, to enable tips of the nano-fingers116 to move toward each other, as discussed in greater detail herein below. Examples of suitable materials for the nano-fingers116 include polymer materials, such as, UV-curable or thermal curable imprinting resist, polyalkylacrylate, polysiloxane, polydimethylsiloxane (PDMS) elastomer, polyimide, polyethylene, polypropelene, fluoropolymer, etc., or any combination thereof, metallic materials, such as, gold, silver, aluminum, etc., semiconductor materials, etc., and combinations thereof.
• The nano-fingers116 are attached to the surface of thesubstrate114 through any suitable attachment mechanism. For instance, the nano-fingers116 are grown directly on thesubstrate114 surface through use of various suitable nano-structure growing techniques. As another example, the nano-fingers116 are integrally formed with thesubstrate114. In this example, for instance, a portion of the material from which thesubstrate114 is fabricated is etched or otherwise processed to form the nano-fingers116. In a further example, a separate layer of material is adhered to thesubstrate114 surface and the separate layer of material is etched or otherwise processed to form the nano-fingers116. In various examples, the nano-fingers116 are fabricated through a nanoimprinting or embossing process in which a template of relatively rigid pillars is employed in a multi-step imprinting process on a polymer matrix to form the nano-fingers116. In these examples, a template may be formed through photolithography or other advanced lithography with the desired patterning to arrange the nano-fingers110 in the predetermined arrangement. More particularly, for instance, the desired patterns may be designed on a mold, by E-beam lithography, photolithography, laser interference lithography, Focused Ion Beam (FIB), self-assembly of spheres, etc. In addition, the pattern may be transferred onto, for instance, silicon, glass, or polymer substrate (PDMS, polyimide, polycarbonate, etc.). Various other processes, such as, etching, and various techniques used in the fabrication of micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS) may also be used to fabricate the nano-fingers116.
• The nano-fingers116 have been depicted as having substantially cylindrical cross-sections. It should, however, be understood that the nano-fingers116 may have other shaped cross-sections, such as, for instance, rectangular, square, triangular, etc. In addition, or alternatively, the nano-fingers116 may be formed with one or more features, such as, notches, bulges, etc., to substantially cause the nano-fingers116 to be inclined to collapse in particular directions. Thus, for instance, two or more adjacent nano-fingers116 may include the one or more features to increase the likelihood that the nano-fingers116 collapse toward each other. Various manners in which the nano-fingers116 may be collapsed are described in greater detail herein below.
• Thearray200 includes a substantially random distribution of nano-fingers116 or a predetermined configuration of nano-fingers116. In any regard, according to an example, the nano-fingers116 are arranged with respect to each other such that the tips of at least two neighboring nano-fingers116 are able to be brought into close proximity with each other when the nano-fingers116 are in a collapsed state. By way of particular example, the neighboring nano-fingers116 are positioned less than about 100 nanometers apart from each other. According to a particular example, the nano-fingers116 are patterned on thesubstrate114 such that neighboring ones of the nano-fingers116 preferentially collapse into predefined geometries, for instance, triangles, squares, pentagons, etc.
• In addition, althoughFIG. 2A depicts the array as having a relatively large number of nano-fingers116 arranged along each row, it should be understood that the array may include any number of nano-fingers116 in each row without departing from a scope of theapparatuses100,100′,100″. In one regard, a relatively large number of nano-fingers116 are provided on thesubstrate114 to generally enhance the likelihood of capturing molecules of an analyte to be tested as adjacent ones of the nano-fingers116 collapse toward each other.
• As also shown inFIG. 2A, Raman-active material nano-particles210 are attached onto the tips of the nano-fingers116. The Raman-active material nano-particles210 comprise a Raman-active material such as, but not limited to, gold, silver, copper, platinum, aluminum, etc., or a combination of these metals in the form of alloys, or other suitable material that is able to support surface plasmons for field enhancement for Raman scattering. In addition, the Raman-active material nano-particles210 may be multilayer structures, for example, 10 to 100 nm silver layer with 1 to 50 nm gold over-coating, or vice versa. The Raman-active material nano-particles210 may have nanoscale surface roughness, which is generally characterized by nanoscale surface features on the surface of the layer(s) and may be produced spontaneously during deposition of the Raman-active material layer(s). By definition herein, a Raman-active material is a material that facilitates Raman scattering from a sample positioned near the Raman-active material during Raman spectroscopy.
• Turning now toFIG. 2B, there is shown a cross-sectional view along a line A-A, shown inFIG. 2A, of thearray200, in accordance with an example. As shown therein, each of thetips208 of the nano-fingers116 includes a respective Raman-active material nano-particle210 disposed thereon. The Raman-active nano-particles210 may be deposited onto thetips208 of the nano-fingers116 through one of, for instance, physical vapor deposition (PVD), chemical vapor deposition (CVD), sputtering, etc., of metallic material, or self-assembly of pre-synthesized nano-particles.
• Although the nano-fingers116 have been depicted inFIGS. 2A-2B as each extending vertically and at the same heights with respect to each other, it should be understood that some of the nano-fingers116 may extend at various angles and heights with respect to each other. The differences in angles and/or heights between the nano-fingers116 may occur, for instance, due to differences arising from manufacturing or growth variances existent in the fabrication of the nano-fingers116 and the deposition of the nano-particles210 on the nano-fingers116, etc.
• As shown inFIG. 2B, the nano-fingers116 are in a first position, in which thetips208 are in a substantially spaced arrangement with respect to each other. Thegaps204 between thetips208 may be of sufficiently large size to enable analyte or other liquid to be positioned in thegaps204. In addition, thegaps204 may be of sufficiently small size to enable thetips208 of at least some of the nano-fingers116 to be drawn toward each other as thesolution120,164 or other liquid evaporates, through, for instance, capillary forces applied on thetips208 as thesolution120,164 deposited on the nano-fingers116 evaporates. In addition, in instances where the analyte comprises a liquid, the nano-fingers116 may collapse toward each other through capillary forces applied on thetips208 as the analyte evaporates.
• Turning now toFIG. 2C, there is shown a cross-sectional view along a line A-A, shown inFIG. 2A, of thearray200, following evaporation of thesolution120,164 and/or the analyte. The view depicted inFIG. 2C is identical to the view depicted inFIG. 2B, except that the nano-fingers116 are depicted in a second position, in which thetips208 of some of the nano-fingers116 have been drawn toward with each other. According to an example, thetips208 of some of the nano-fingers116 may be in and may remain in relatively close proximity to with each other for a period of time due to the capillary forces applied on adjacent ones of the nano-fingers116 during and following evaporation of thesolution120,164 in thegaps204 between thetips208.
• In any event, and in one regard, thetips208 of the nano-fingers116 are caused to be drawn toward each other as shown inFIG. 2C to cause an analyte molecule to be tested to substantially be trapped between the Raman-active material nano-particles210 positioned onadjacent tips208. In this regard, a relatively small gap, for instance, a few nanometers or less, between the adjacent ones of the Raman-active material nano-particles210 positioned on thetips208 may remain when analyte molecules are trapped between theadjacent tips208. By substantially trapping an analyte molecule to be tested between the Raman-active material nano-particles210 that are in relatively close proximity to each other, SERS on the analyte molecule may be enhanced because the relatively small gaps between the Raman-active material nano-particles210 create “hot spots” having relatively large electric field strengths. Substantially trapping an analyte molecule here is intended to indicate that the analyte molecule may either be trapped between at least two Raman-active material nano-particles210 that are in relatively close proximity to each other or attached on one of the at least two Raman-active material nano-particles210 that are in relatively close proximity to each other.
• With reference now toFIG. 3, there is shown a simplified block diagram300 of a portion of thesensing application apparatus100 depicted in any ofFIGS. 1A-1C, according to an example. Generally speaking, the block diagram300 depicts in greater detail operations performed to illuminate and detect Raman scattered light emitted from ananalyte310.
• As shown inFIG. 3, molecules of ananalyte310 to be tested are depicted as being positioned in contact with and in close proximity to the Raman-active material nano-particles210. Some of theanalyte molecules310 are also depicted as being trapped between a couple adjacent ones of the Raman-active material nano-particles210. According to an example, theillumination source106 is to direct a beam ofillumination130 to locations of different subsets of the nano-particles210 to thereby enable testing to be performed on the various locations of the Raman-active material nano-particles210. The placement of the beam ofillumination130 may be changed through any of a variety of different manners. For instance, the direction of the beam ofillumination130 may be varied by changing an angle at which the beam is emitted from theillumination source106. As another example, a movable mirror may be implemented to vary the direction in which the beam ofillumination130 is directed. As a further example, thestage112 may be moved with respect to the beam ofillumination130.
• In any regard, the beam ofillumination130 illuminates the molecules of theanalyte310 and the Raman-active material nano-particles210. Illumination of the Raman-active material nano-particles210 causes hot spots of relatively large electric field strength to occur. The hot spots are increased at the locations where the Raman-active material nano-particles210 are in relatively close proximity to each other, for instance, within a few nanometers, or are in contact each other. The electric fields generated between the Raman-active material nano-particles210 that are in relatively close proximity to each other generally enhance the rate at which Raman light is scattered by theanalyte molecules310 positioned at or near the contact locations. The Raman scattered light, which is represented by thearrow132, is shifted in frequency by an amount that is characteristic of particular vibrational modes of theanalyte molecules310. Thedetector108 is to collect the Raman scattered light132 and spectral analysis is to be performed on the collected Raman scattered light132 either at theapparatus100,100′,100″ or at a device external to theapparatus100,100′,100″.
• Although the Raman scattered light132 has been depicted as being directed toward thedetector108, the Raman scattered light132 is emitted in multiple directions. In this regard, some of the Raman scattered light132 may be directed into thestage112, which, in one example, comprises an optical waveguide. In addition, theillumination source106 may cause the beam ofillumination130 to be directed into thestage112. In this example, Raman scattered light132 may be generated in thestage112 as a result of theanalyte310 coupling to an evanescent field of a waveguide mode generated by theillumination130 being emitted through thestage112. In addition, thedetector108 may be positioned to detect the waves generated in thestage112 from the Raman scattered light132. In any regard, thedetector108 may include a filter to filter out light originating from theillumination source106, for instance, through use of a grating-based monochrometer or interference filters. Thedetector108 may alternatively be positioned at other locations with respect to the nano-fingers116, for instance, below thestage112 inFIG. 3.
• Thedetector108 is generally to convert the detected Raman scattered light132 into electrical signals. In some examples, thedetector108 is to output the electrical signals to other components (not shown) that are to process the electrical signals, such as, a computing device, through theinterface110. In other examples, thedetector108 is equipped with the processing capabilities.
• Turning now toFIG. 4, there is shown a flow diagram of amethod400 for performing a sensing application on ananalyte310 introduced onto a plurality of nano-fingers116, according to an example. It should be understood that themethod400 may include additional operations and that some of the processes described herein may be removed and/or modified without departing from a scope of themethod400.
• Prior to or during implementation of themethod400, theanalyte310 may be introduced onto the nano-fingers116 either directly or indirectly. By way of example, theanalyte310 may be mixed with thesolution120 prior to dispensing of the solution/analyte mix onto the nano-fingers116. As another example, theanalyte310 may be contained in asecond reservoir160 and may be delivered onto the nano-fingers116 by asecond dispenser162 in fluid communication with thesecond reservoir160. As a further example, theanalyte310 may be present in the ambient environment around thesensing application apparatus100,100′,100″ and may be introduced through an opening in the housing140 of thesensing application apparatus100,100′,100″. Theanalyte310 may alternatively be introduced in various other manners.
• Atblock402, asolution120 from areservoir102 is dispensed onto the nano-fingers116. As discussed above, adispenser104 in fluid communication with thereservoir102 is operated to controllably dispense thesolution120 onto the nano-fingers116. Thus, for instance, thedispenser104 may be operated to dispense thesolution120 onto a predefined subset of the nano-fingers116. In addition, or alternatively, thedispenser104 may be operated to dispense a predetermined volume of thesolution120 onto the nano-fingers116.
• Atblock404, heat is applied onto the solution to cause the solution to evaporate. Heat may also be applied onto the analyte atblock404. In one example, the heat is applied by theillumination source106. In this regard, theillumination source106 performs both functions of evaporating thesolution120 and illuminating theanalyte310. In another example, the heat is applied by a separate heating element (not shown), for instance, a heating element, such as a resistor, provided in thestage112 that applies heat onto thesubstrate114 and the nano-fingers116. The separate heating element may also comprise, for instance, a separate light source, thepower supply150, etc.
• In any regard, and as discussed above, the nano-fingers116 are positioned sufficiently close to each other to cause at least some of the nano-fingers116 to be drawn toward each other as the solution220 (and the analyte310) evaporates due to capillary forces applied onto the nano-fingers116. In addition, in instances where theanalyte310 is present during the drawing together of the nano-fingers116, portions of theanalyte310 are likely to be trapped between and/or positioned adjacent to the adjacent tips or the Raman-active material nano-particles210 positioned on the tips.
• At block406, thenano fingers116 and theanalyte310 are illuminated by theillumination source106 to cause Raman scattered light132 to be emitted from theanalyte310. As discussed above, the Raman active nano-particles210 provided on the tips of the nano-fingers116, and particularly the Raman active nano-particles210 that are in relatively close proximity to or in contact with each other, enhance the production of Raman scattered light132 from theanalyte310 by concentrating or otherwise enhancing an electromagnetic field in or around theanalyte310.
• Atblock408, the Raman scattered light is detected by thedetector108.
• According to an example, themethod400 is repeated a number of times to detect Raman scattered light132 emitted from portions of theanalyte310 positioned on different subsets of the nano-fingers116. In this example, the positions at which the portions of theanalyte310 may be varied between each iteration of themethod400 through manipulation of at least one of the positions of thestage112 and the location at which the beam ofillumination130 illuminates the nano-fingers116. In addition, and according to an example, the different subsets of nano-fingers116 at which the portions of theanalyte310 are tested may have received different types ofsolutions120,164 atblock402. In this example, and as shown inFIG. 1C,different solutions120,164 may be dispensed onto different subsets of nano-fingers116 bydifferent dispensers104,162. As such, for instance,different solutions120,164 that interact differently with ananalyte310 and/or different types ofanalytes310 may be deposited onto different subsets of nano-fingers116 and tested during subsequent iterations of themethod400.
• Turning now toFIG. 5, there is shown a flow diagram of amethod500 for communicating electrical signals representative of the detected Raman scattered light to a destination receiver, according to an example. It should be understood that themethod500 may include additional processes and that some of the processes described herein may be removed and/or modified without departing from a scope of themethod500.
• Atblock502, the Raman scattered light detected atblock408 is converted into electrical signals. In addition, atblock504, the electrical signals are communicated to a destination receiver, for instance, through theinterface110. As discussed above, theinterface110 may comprise a wireless interface through which the electrical signals are wirelessly communicated to the destination receiver. According to a particular example, theinterface110 is to a cloud environment and the electrical signals are submitted to the cloud environment for retrieval and processing by a processing device, such as, a computer, a server, etc.
• Some or all of the operations set forth in themethods400 and500 may be contained as a utility, program, or subprogram, in any desired computer accessible medium. In addition, themethods400 and500 may be embodied by machine readable instructions, which may exist in a variety of forms both active and inactive. For example, they may exist as source code, object code, executable code or other formats. Any of the above may be embodied on a non-transitory computer readable storage medium. Examples of non-transitory computer readable storage media include conventional computer system RAM, ROM, EPROM, EEPROM, and magnetic or optical disks or tapes. It is therefore to be understood that any electronic device capable of executing the above-described functions may perform those functions enumerated above.
• Turning now toFIG. 6, there is shown a schematic representation of asensing application apparatus600, such as any of thesensing application apparatuses100,100′,100″ depicted inFIGS. 1A-1C, according to an example. Theapparatus600 includes acontroller602, such as a processor, an ASIC, etc. Thecontroller602 is depicted as being in communication with adispenser604, anillumination source606, adetector608, anactuator610, aninterface612, and a computerreadable medium614 over abus618. For example, thebus618 may be an EISA, a PCI, a USB, a FireWire, a NuBus, or a PDS. Although not shown, theapparatus600 may include additional components, such as, a display, input interface, etc., through which a user may input instructions and/or receive information.
• The computerreadable medium614 comprises any suitable medium that participates in providing instructions to thecontroller602 for execution. For example, the computerreadable medium614 may be non-volatile media. As shown inFIG. 6, the computerreadable medium614 stored thereon a set ofsensing application instructions616.
• The set ofsensing application instructions616 includes a set of machine readable instructions for controlling operation of theapparatus600 components in implementing themethods400 and500 respectively depicted inFIGS. 4 and 5. Thesensing application instructions616 may thus comprise instructions to control thedispenser604 to dispense asolution120 onto the nano-fingers116, to control theillumination source606 to apply heat onto thesolution122, to control theillumination source606 to illuminate the nano-fingers116 and portions of an analyte, to control thedetector608 to detect Raman scattered light emitted from the analyte, and to control the actuator(s)610 to vary at least one of a position of thesubstrate114 and a beam ofillumination130 emitted from theillumination source130. In addition, thesensing application instructions616 may also include machine-readable instructions to control thedetector608 to convert the detected Raman scattered light into electrical signals and to communicate the electrical signals to a destination receiver.
• In certain examples, the processes may be at least partially implemented in digital electronic circuitry, or in computer hardware, machine readable instructions (including firmware and software), or in any combination thereof, as also discussed above.
• What has been described and illustrated herein is an example along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Many variations are possible within the spirit and scope of the subject matter, which is intended to be defined by the following claims—and their equivalents—in which all terms are meant in their broadest reasonable sense unless otherwise indicated.

Claims (15)

What is claimed is:

1. An apparatus for performing a sensing application, said apparatus comprising:

a reservoir to contain a solution;

a dispenser to dispense the solution from the reservoir;

a substrate having a plurality of nano-fingers positioned to receive the dispensed solution, wherein the plurality of nano-fingers are flexible, such that the plurality of nano-fingers are configurable with respect to each other;

an illumination source to illuminate the received solution, an analyte introduced around the plurality of nano-fingers, and the plurality of nano-fingers, wherein light is to be emitted from the analyte in response to being illuminated; and

a detector to detect the light emitted from the analyte.

2. The apparatus according toclaim 1, wherein the plurality of nano-fingers comprise respective tips, said apparatus further comprising:

Raman-active material nano-particles attached to respective tips of the plurality of nano-fingers.

3. The apparatus according toclaim 2, wherein the plurality of nano-fingers are to be collapsed toward each other such that the Raman-active material nano-particles attached to the respective tips of subsets of the plurality of nano-fingers are brought into close proximity or in contact with each other.

4. The apparatus according toclaim 1, wherein the dispenser is to dispense the solution onto a subset of the plurality of nano-fingers, and wherein the plurality of nano-fingers are positioned in sufficiently close proximity to each other to cause the subset of the plurality of nano-fingers to collapse toward each other as the solution evaporates through application of capillary forces onto the plurality of nano-fingers in the subset by the solution.

5. The apparatus according toclaim 4, further comprising:

a heating element to increase the rate at which the solution evaporates.

6. The apparatus according toclaim 4, wherein the illumination source is to apply heat to the solution on the subset of the plurality of nano-fingers to substantially enhance evaporation of the solution.

7. The apparatus according toclaim 1, further comprising:

a movable stage; and

wherein the substrate is positioned on the movable stage, and wherein the movable stage is to be moved from a location to receive the solution from the dispenser to a location to be illuminated by the illumination source.

8. The apparatus according toclaim 1, wherein the detector is to generate signals representative of the detected light, said apparatus further comprising:

a wireless interface to wirelessly communicate the signals to a destination receiver that is externally located with respect to a housing of the apparatus.

9. The apparatus according toclaim 1, further comprising:

a second reservoir to contain a second solution; and

a second dispenser to dispense the second solution from the reservoir onto a second subset of the plurality of nano-fingers that differs from a subset of the plurality of nano-fingers onto which the dispenser is to dispense the solution from the reservoir, wherein the illumination source is to further illuminate the dispensed second solution and wherein the detector is to detect light emitted from an analyte introduced around the second subset of the plurality of nano-fingers.

10. The apparatus according toclaim 1, further comprising:

a housing that encapsulates the reservoir, the dispenser, the substrate, the illumination source, and the detector, wherein the housing is sized for handheld use.

11. A method for performing a sensing application on an analyte introduced onto a plurality of nano-fingers, said method comprising:

dispensing, from a reservoir, a solution onto the plurality of nano-fingers, wherein Raman-active material nano-particles are attached to respective tips of the plurality of nano-fingers;

applying heat onto the solution to cause the solution to evaporate, wherein evaporation of the solution causes tips of adjacent ones of the plurality of nano-fingers to be drawn toward each other through capillary forces applied on the tips by the solution, and wherein molecules of the analyte are at least one of trapped between and positioned adjacent to the Raman-active material nano-particles attached to the respective tips that have been drawn toward each other;

illuminating the Raman-active material nano-particles and the analyte to cause enhanced Raman scattered light to be emitted from the analyte; and

detecting the enhanced Raman scattered light.

12. The method according toclaim 11, further comprising:

converting the detected Raman scattered light into electrical signals; and

wirelessly communicating the electrical signals.

13. The method according toclaim 11, wherein illuminating the plurality of nano-fingers further comprises illuminating the plurality of nano-fingers with an illumination source, and wherein applying heat onto the solution further comprises applying heat from the illumination source.

14. The method according toclaim 11, said method further comprising:

dispensing, from a second reservoir, a second solution onto a second subset of the plurality of nano-fingers, wherein applying heat onto the solution further comprises applying heat onto the second solution;

illuminating the Raman-active nano-particles and the analyte around the second subset of the plurality of nano-fingers to cause enhanced Raman scattered light to be emitted from the analyte near the second subset of the plurality of nano-fingers; and

detecting the enhanced Raman scattered light emitted from the analyte near the second subset of the plurality of nano-fingers.

15. A non-transitory computer readable storage medium on which is stored machine readable instructions, that when executed by a processor are to implement a method for performing a sensing application on an analyte introduced onto a plurality of nano-fingers, said machine readable instructions comprising code to:

dispense, from a reservoir, a solution onto the plurality of nano-fingers, wherein Raman-active material nano-particles are attached to respective tips of the plurality of nano-fingers;

apply heat, by an illumination source, onto the solution to cause the solution to evaporate, wherein evaporation of the solution causes tips of adjacent ones of the plurality of nano-fingers to be drawn toward each other through capillary forces applied on the tips, and wherein molecules of the analyte are at least one of trapped between and positioned adjacent to the Raman-active material nano-particles that are attached to the respective tips that have been drawn toward each other;

illuminate, by the illumination source, the Raman-active material nano-particles and the analyte to cause Raman scattered light to be emitted from the analyte;

detect, by a detector, the Raman scattered light;

convert the detected Raman scattered light into electrical signals; and

communicate the electrical signals to a destination receiver.

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